ANIMINE CoRouge 2022 03 Feed & Additives - Copper in Ruminants (VK)

1. ISSUE FOCUS COPPER IN RUMINANTS: FROM ESSENTIAL TO TOXIC Valérie Kromm Product Manager Animine “Copper (Cu) bioavailability for ruminants is mainly determined by sulfur, molybdenum and iron levels in the diet. Thus, complete forage analyses are essential to fine tune the quantity of Cu needed to meet the animal requirements, without forgetting drinking water which can be a significant source of iron and sulfur for the animal.” C (Cu) is an essential trace element in ruminants. As it is required in many key enzymes, any sub-clinical deficiency will impair animal health, fertility and production performance. genetic variation observed in Cu absorption can also influence Cu requirements. Literature mentions in particular higher requirements in Scottish Blackface than in Texel sheeps and in Jersey than in Holstein Friesians cows. OPPER: ESSENTIAL FOR RUMINANTS It has long been recognized that copper LIMITATIONS OF REQUIREMENTS SYSTEM With the most recent research on dairy cattle mineral nutrition, guidelines are becoming more and more accurate in defining dietary require- ments. Still, some limitations in the system do ex- ist. Those requirements systems do not take into account rumen effect, ‘non absorbed’ effects or antagonistic effect. That’s why adjustments need to be done despite the high precision of the latest data. Cu requirements and maximum Cu level autho- rized in the European Union are presented in Fig- ure 1. For bovine, the requirements are around 10 mg/kg DM with higher values for dairy cows in the close-up period and in the first weeks after parturi- tion. Following the 8th revised edition of the Nu- trient Requirement of Dairy Cattle (NASEM 2021) little change is observed in requirements in Cu for average lactating cows (11 mg/kg DM). However, for dry cows, requirements increased 40% (17 mg/ kg DM) while for high producing cows, require- ments decreased 45% (9 mg/kg DM). Because of the small margin between Cu defi- ciency and Cu toxicity and because the high sus- ceptibility of Cu to bind antagonists in the rumen, Cu is a good example of an element to adjust close- ly in ruminants. Higher values are recommended for caprine (up to 25 mg/kg DM) but lower for ovine (up to 10 mg/ kg DM) which are highly sensitive to excess Cu. A March 2022 58 FEED & ADDITIVE MAGAZINE

2. ISSUE FOCUS Figure 1 - Cu requirements and maximum Cu dietary level authorized in the EU for ruminants (mg/kg complete feed) Bovines before the start of rumination Other bovines Small ruminants Beef Dairy Ovines Caprines NRC, USA (2000, 2021, 2007) 10 10 9-18 4-8 15-25 GfE, DE (1995, 2001, 2003) - 8-10 10 - 10-15 Requirements CVB, NL (2005) 10 11-13 7-17 6-7 8 Agroscope, CH (2006, 2009) 6 10 10-15 5 8 INRA, FR (2018) 10 - 10 15-25 30 Maximum Cu dietary levels authorized1 15 15 35 1 Regulation (EU) 2018/1039 RISK OF SECONDARY DEFICIENCY Secondary deficiency happens when even at proper level of Cu supplementation, the presence of oth- er dietary factors interferes with mineral absorption and metabolism. This phenomenon is the main cause of Cu deficiency in ruminants. Sulfur (S), molyb- denum (Mo) and iron (Fe) are the most important dietary factors to negatively impact Cu absorption. , , an international and independent supplier of precision minerals POTENTIATED ZINC The signs of Cu deficiency vary from mild symptoms such as loss of coat condition and poor growth, to more severe symptoms like in- fertility and diarrhea. MONOVALENT COPPER HIGHLY PURIFIED MANGANESE As forage and diet compositions are seasonal and variable from farm to farm, secondary deficiencies are difficult to predict. Therefore, Cu in ruminant diets is usually supplemented well above nutri- tional requirements, to guarantee Cu absorption regardless of the presence of antagonists. POTENTIATED ZINC OVERSUPPLY IN DAIRY CATTLE While in the past Cu deficiencies used to occur in grazing ruminants, researchers have observed in a High High Concentration Flowability Safety standards Safety standards Concentration Flowability Stability Bioavailability Animal performance Animal performance Stability Bioavailability 59 March 2022 FEED & ADDITIVE MAGAZINE www.animine.eu

3. ISSUE FOCUS growing number of countries in Europe, America and Oce- ania, an increased concentra- tion of Cu in the liver of dairy cow herds over the years. toxicity with animals often dying within 24-48h. A growing number of le- thal cases reported by veter- inarians showed that such si- lent intoxication is spreading in dairy herds, which urges the development of strategies to monitor herd Cu status and amplify the awareness of farmers for Cu toxicity. A study carried out at the University of Nottingham (UK), showed that most sheep (60%) have normal liver Cu and are more like- ly to be deficient. The same study showed that 70% of dairy cattle in the UK have high Cu status (Figure 2) with 60% of the farms feed- ing animals with Cu levels above 20 mg/kg DM and 8% above the legal limit. Recent research indicates that Cu already accumulates in bovine liver at dietary lev- els recommended by the in- dustry, and that cattle could be less tolerant to Cu than previously thought. Figure 2 – Liver Cu status of dairy cow in the UK (µmol/kg DM) (University of Nottingham) (Image courtesy by Dr. Clarkson) The main reasons report- ed were misinformation of farmers and the fear of deficiency. In addition, the multichannel supply of trace elements (via concen- trates, mineral feeds, nutritional supplements…) and the variability in forages composition make it difficult to monitor total Cu supplementation. CONCLUSION This topic highlights the importance of preci- sion mineral feeding in order to guarantee an effi- cient supply of Cu, safe for the animal and for the environment. Cu bioavailability for ruminants is mainly deter- mined by sulfur, molybdenum and iron levels in the diet. Thus, complete forage analyses are essential to fine tune the quantity of Cu needed to meet the animal requirements, without forgetting drinking water which can be a significant source of iron and sulfur for the animal. CHRONIC COPPER TOXICITY Prolonged Cu intake, above requirements, can lead to chronic toxicity which is the result of the slow accumulation of Cu in the liver during a long period of time. At the opposite of acute toxicity, Chronic Copper Poisoning can remain ‘silent’ for months or years, before the toxicity is apparent. The choice of the source of copper supplemented in the feed is also of importance. Indeed, Cu sourc- es with known physicochemical characteristics and dissolution kinetics can help to select the one which is the less susceptible to form complexes in the ru- men. Monovalent copper oxide, combines high bioavailability with a low solubility at rumen pH. This innovative source of Cu will help to restrict the need for higher Cu dosages in ruminant diets and to preserve animal productivity, health and welfare. The elevation of liver enzymes in the blood, that indicates hepatopathy caused by high levels of Cu, can be related to a wide range of other diseases. Ad- ditionally, clinical signs are mild and with low mor- bidity which can often be overseen by veterinarians. Increase in blood Cu is only seen as a second stage when the liver is overloaded and Cu is re- leased into the bloodstream. This causes acute March 2022 60 FEED & ADDITIVE MAGAZINE